What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:-heart disease-liver disease-lung or breathing disease, like asthma-an unusual or allergic reaction to dantrolene, other medicines, foods, dyes, or preservatives-pregnant or trying to get pregnant-breast-feeding

What should I watch for while using this medicine?

Your condition will be monitored carefully while you are receiving this medicine.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells. Alcohol may interfere with the effect of this medicine. Avoid alcoholic drinks.

If you are taking another medicine that also causes drowsiness, you may have more side effects. Give your health care provider a list of all medicines you use. Your doctor will tell you how much medicine to take. Do not take more medicine than directed. Call emergency for help if you have problems breathing or unusual sleepiness.

This medicine can make you more sensitive to the sun. Keep out of the sun. If you cannot avoid being in the sun, wear protective clothing and use sunscreen. Do not use sun lamps or tanning beds/booths.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:

-allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue -breathing problems -seizures -signs and symptoms of liver injury like dark yellow or brown urine; general ill feeling or flu-like symptoms; light-colored stools; loss of appetite; nausea; right upper belly pain; unusually weak or tired; yellowing of the eyes or skin -unusually weak or tired Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):